Liquid cooling is all the rage again in servers, and Dell has jumped into the pool.

The Round Rock, Texas-based computer maker has struck a deal with a component and industrial equipment maker to sell advanced cooling systems and services to data center owners.

Financial terms of the deal between Dell and Emerson Network Power were not disclosed. The agreement was announced Thursday.

One type of supplemental cooling technology from Emerson is called the Liebert XD. The XD consists of refrigerant-filled pipes that snake around the server racks in a data center. When the liquid refrigerant is in the pipes near the servers, it absorbs the heat coming off the computers, turns into a gas, and then gets pumped back to a cooling unit. The cooling unit then turns it back into a liquid for another cycle.

The liquid system cuts the cooling power load by about 30 percent to 50 percent as compared with other types of cooling systems, said Fred Stack, vice president of marketing for Emerson, in a presentation in San Francisco. Overall, cooling can consume about half a data center's electricity. By using a more energy efficient cooling method, IT managers can realize cost savings and, in turn, possibly dedicate more of their budget to servers, Stack said.

"The main reason is that we've got the cooling near the (servers)," he said. "We get the cooling coils as close as possible to the computers."

In traditional systems, air conditioners blow chilled air up through the tiles in the floor.

So far, around 6,000 server racks are chilled with the Liebert XD, said Stack.

IBM and Hewlett-Packard have similar liquid cooling systems, but Stack pointed out that both companies are using water rather than a refrigerant. The refrigerant, he asserted, is far better at absorbing heat.

Computer architects have sporadically used liquid systems to cool computers and components for years. Most of these systems, however, have required pumps, which have caused concerns about reliability and energy efficiency. In the past, the tradeoff has generally favored air conditioning.

Many companies have been trying to popularize liquid cooling systems that could fit inside a PC or server. Cooligy, which was acquired by Emerson, has promoted a pump system for a few years, while Nanocoolers has devised a passive liquid cooling system. Others include Boston Microsystems.

Such systems could begin to hit the market in a few years, but customer acceptance could take time.